THERMAL-STABILITY AND OXYGEN NONSTOICHIOMETRY OF BSCCO SUPERCONDUCTORS

Investigation of HTSC thermal stability in air shows that the samples, containing 75% of 2223 phase and 25% of 2212 phase, at 800-degrees-C does not change phase ratio and transition parameters. At lower annealing temperature (700-degrees or 750-degrees-C) there appear "tail" on resistive curve and traces of new phases. Subsequant annealing of these samples at 800-degrees-C restores initial parameters. The highest oxygen nonstoichiometry index-delta of Pb-containing 2223 phase equal to 0.20 +/- 0.01 is reached at 750-degrees-C, i.e. at lower boundary of highest homologue thermal stability.